Four years after a humiliating defeat here that tarnished his presidential aspirations, Mitt Romney scored the most unsatisfying of victories in the Iowa caucuses Tuesday, barely edging Rick Santorum and underscoring the challenges he faces as he chases the Republican nomination.

Santorum, riding a sudden wave of support from conservatives not sold on Romney, came up short by 8 votes when the official results were finally announced at 2:33 a.m. EST.

It was the closest nominating contest in memory and evoked memories of the 2000 presidential election, decided by just 537 Florida votes. Turnout was just over 122,000, a record for the Iowa GOP caucus.

"Game on!" Santorum declared at 12:18 a.m. Wednesday from his campaign headquarters, vowing to fight through New Hampshire, South Carolina and Florida.

"On to New Hampshire!" Romney told supporters at a hotel in downtown Des Moines a while later. He congratulated Santorum but continued to keep his focus on President Barack Obama, trying to maintain an image as the inevitable nominee.

Ron Paul cast his third-place finish as a victory, too, proclaiming only he had the organization to take on Romney. Newt Gingrich came in fourth, followed by Rick Perry, Michele Bachmann and Jon Huntsman, who did not compete in Iowa.

In the first concession speech of his political career, Perry told supporters he's returning to Texas to "determine whether there is a path forward."

Santorum only days ago emerged as a contender after languishing at the bottom of the polls. He worked Iowa the old-school way, going county to county in a Ram 1500 pickup truck to meet with voters in 380 town hall meetings. He ascended as voters embraced then dropped other Romney alternatives.

"The conventional wisdom is Romney is more electable, but there are just too many questions I have about his history in terms of life and social values," said Santorum supporter Tom Henriksen, a 45-year-old software engineer from Pleasant Hill. "I don't know what I would do if he's the nominee."

Today, the race shifts to New Hampshire, where Romney, former governor of Massachusetts, has a big lead. A Suffolk University/7 News poll released Tuesday showed Romney with 43 percent of the vote, 27 points ahead of second-place Paul.

New Hampshire's primary is Jan. 10, followed by South Carolina on Jan. 21 and Florida on Jan. 31. Trying to signal his reach, Romney on Tuesday announced a TV ad in Florida, where he has the best organization of any candidate and is eyeing more Electoral College votes than all the earlier states combined.

If he holds in New Hampshire and does well in South Carolina — perhaps the last stand for a rival to make the case as the strongest conservative — Romney effectively can clinch the nomination in Florida.

Romney played it safe in Iowa at first, wary of the state's rejection of him in the 2008 caucuses. He was defeated by Mike Huckabee, who, like Romney's rivals today, saw himself as the true conservative.

One by one, Romney alternatives overtook him in the polls, only to slide behind under growing scrutiny and blunders.

Increasingly confident, Romney only recently started to make regular visits to Iowa.

His finish was helped in no small way by the millions in attack ads unleashed on his rivals in recent weeks. Gingrich, just weeks ago the front-runner, complained bitterly about the ads in campaign stops over the past few days but resisted calls to respond with equal negativity.

Gingrich pledged a more aggressive pushback in New Hampshire, backing it up by calling Romney a liar on national TV Tuesday morning for denying a role in the negative ads financed by third-party groups.

Restore our Future, one of the pro-Romney "super PACs," spent $4.1 million in ads, all of them negative.

"He's not telling the American people the truth. It's just like his pretense that he's a conservative," Gingrich said on CBS' The Early Show. "I just think he ought to be honest to the American people and try to win as the real Mitt Romney, not try to invent a poll-driven, consultant-guided version that goes around with talking points."

Voters waking up to the New Hampshire Union Leader will see a full-page ad labeling Gingrich a "Bold Reagan Conservative" and Romney a "Timid Massachusetts Moderate."

Romney has been repeatedly accused of shifting his positions to the right, from abortion to gun rights and gay marriage. Many conservatives continue to doubt him, a weakness that Santorum could still mine. Romney could also face challenges from evangelical Christians, who are skeptical of his Mormon faith.

Iowa's record in picking the nominee is mixed, but it does help narrow the field. If lesser candidates drop out, that could prompt conservative voters to coalesce more strongly behind one Romney alternative.

Before the results, Perry had planned to focus on South Carolina, where his Christian background could play well.

"Mitt Romney has got a real problem when it comes to consistency," Perry said on CNN. "Those folks in South Carolina, I can promise you, they're not going to buy a pig in a poke, so to speak, and a Massachusetts governor that put individual mandates in place that Obama took as the model to create Obamacare is not going to sell in South Carolina."

Santorum said was looking south, too.

"We're absolutely coming down to Florida," he said Tuesday morning after speaking at a Rock the Caucus event at a high school in West Des Moines. "We've got a lot of folks in Florida that have been contacting us. We've been signing up folks and getting coordinators in place."

Santorum would have to pick up support quickly. In the September Presidency 5 straw poll in Orlando, he placed fourth behind Herman Cain, Perry and Romney.

Tuesday's results signal that Romney is successfully making the case that he is the strongest candidate to take on Obama, a theme he sounded repeatedly in Iowa over the past few days. Romney is highlighting his business background as central to fixing the economy.

Democrats, too, see Romney as the chief threat and sent a team to Iowa this week to attack him. Florida U.S. Rep. Debbie Wasserman Schultz, chairwoman of the Democratic National Committee, assailed his record in a series of television interviews Tuesday and a news conference with reporters.

"Mitt Romney has made it clear he will say and do anything to get elected — and that includes trying to cover up previous moderate-to-liberal positions he took as a Massachusetts politician to make sure voters never know the truth about his record," Wasserman Schultz said.

Obama delivered a video message to Democratic supporters and his campaign bought ads that covered the home page of the Des Moines Register website. Iowa, despite its small size, is important for Obama in the general election and the campaign has more staffers and offices than any of the Republicans.

Paul benefited from an intense backing of civil libertarians and young voters who bought into his anti-politician persona and promise to gut the federal government, strip away regulations and end U.S. military engagement abroad.

Many of Paul's supporters seemed content with his role in stirring the debate rather than thinking he can get the nomination.

"It's going to be hard, let's be real here," said Joseph Howe, a 31-year-old insurance agent from Des Moines who caucused for Paul. "There are some people out there who are more traditional and are scared off a little by his points of view.

"But," he added, "at the very least it sends a message. Republicans are going to lose this entire party if they don't open their minds to other points of view."

Information from the New York Times was used in this report.

washington, D.C.

on gop's night, obama thanks backers in iowa

President Barack Obama thanked his Iowa supporters Tuesday evening and warned them to prepare for a difficult re-election fight against the eventual Republican nominee in the months to come. "It's going to be a big battle," Obama said in a video teleconference with Iowa Democrats participating in the first voting of the year. "I hope you guys are geared up." Obama is without a serious primary rival. But on an evening when attention was focused on the Republican contest, he chose to address Iowa Democrats, who set him on his way to the presidency four years ago. His campaign purchased a high-profile advertisement that ran Tuesday on the Des Moines Register home page, showcasing those pledges and indicating that each had been accomplished. But the nation's politics have grown even more split along partisan lines and acrimonious in tone over the past four years, leaving many less enthusiastic about the president who promised unity and change. Obama's approval rating sits at 45 percent, according to the most recent Gallup survey.

Washington Post

Des Moines, Iowa

Paul's tweet tweaks Huntsman

Former Utah Gov. Jon Huntsman has been hitting Rep. Ron Paul in recent days, but Paul struck back Tuesday night in a Twitter message taunting Huntsman: "@jonhuntsman we found your one Iowa voter, he's in Linn precinct 5, you might want to call him and say thanks.'' When the race moves to New Hampshire, Huntsman and Paul will be competing for some of the same voters.

POLITICO

Up next: New Hampshire

Iowa picks corn and New Hampshire picks presidents, former New Hampshire Gov. John Sununu famously quipped in 1988. Condescending, sure, but Sununu did have a point about the Granite State being a more representative barometer than Iowa. Iowa's caucus system, essentially a series of town meetings, draws a fraction of that state's overall electorate, while New Hampshire's primary is a more conventional election that can draw a fairly broad spectrum of voters. In New Hampshire, for instance, Democrats and independents can show up on election day and register as Republicans if they want to participate.

That makes New Hampshire's Jan. 10 primary an opportunity for candidates who appeal to swing voters, and it's one reason former Utah Gov. Jon Huntsman is banking his campaign on a strong showing there.

Romney, as the former governor of Massachusetts and owner of a New Hampshire vacation home, is heavily favored. Recent polls show him averaging 41 percent support, followed by Ron Paul with 19 percent, Newt Gingrich with 13, and Huntsman with 11, according to RealClearPolitics. Romney's home-turf advantage gives other candidates an excuse to downplay the state's significance, and Michele Bachmann and Rick Perry were scheduled to head straight to South Carolina, though Perry changed plans after Iowa's results, saying he'd return to Texas instead.